IB/qib: Use request_firmware() to load SD7220 firmware

Extract the microcode for the QLogic QLE7220 series IB HCA and use the
kernel microcode request facility to load the microcode.  This
supports Debian Linux's requirements to separate microcode which
doesn't have open source code available from the device driver.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Roland Dreier <rolandd@cisco.com>